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The four major Atlantic hurricanes that spun toward the Caribbean in the past month were fueled by record warm seas and formed in an unprecedented 20 days. With 10 weeks left in the hurricane season, more may be coming.

The storms that were born off west Africa gathered strength by absorbing the ocean’s heat and swelled into Category 4-level hurricanes on the five-step Saffir-Simpson scale. While none hit land at full speed, each packed winds of at least 131 miles an hour, stronger than Katrina’s Category 3 winds when it devastated New Orleans in 2005.

After Igor churned past Bermuda Monday and cut power to two-thirds of the island’s residents, Tropical Storm Lisa formed yesterday in the east Atlantic. While the six-month season is past its statistical peak, forecasters and insurers said warmer seas can lengthen the danger period to property, from beach homes in Florida to rigs and refineries in the oil-rich Gulf of Mexico.

“The hotter the water, the higher the octane level, and there [are] going to be far more Category 4 and 5 hurricanes,’’ said Jim Rouiller, an Air Force meteorologist for 20 years who works for Planalytics Inc. in Berwyn, Pa.

The season may be busy for another month, said Simon Young, chief executive of the insurer Caribbean Risk Managers. “All the ingredients’’ were in place for major hurricanes to form this year, he said.

The National Hurricane Center predicts 2010 will have as many as 20 storms of at least 39 mile-per-hour winds, meaning they will be named, compared with 11 in a typical year. Lisa’s formation yesterday brought this year’s tally to 12. The Miami-based center has identified five major hurricanes in 2010 compared with two in an average season when waters are cooler.

The season runs June through November, peaking around Sept. 10. After that, major storms can and do still form. In 2005, Hurricane Rita’s winds peaked at 178 miles per hour on Sept. 22.

The Atlantic has had record temperatures since March and by the end of August a swath of the ocean was 3 degrees above average, said Gerry Bell, lead hurricane forecaster at the National Oceanic and Atmospheric Administration in Camp Springs, Md. The records date to 1854.

Hurricanes gather energy from the warmth of the sea, one of several factors that increase their punch. This year’s record warmth may help prolong the season as will conditions associated with La Nina, a weather pattern that reduces high-altitude winds that impede Atlantic storm development.